Assessment of Soil Erosion Dynamics Using the GIS-Based RUSLE Model: A Case Study of Wangjiagou Watershed from the Three Gorges Reservoir Region, Southwestern China

The adjacent agricultural watershed is a vital component of the Three Gorges Reservoir Region (TGRR); however, it is affected by serious soil erosion. Assessing soil erosion dynamics in such watersheds is useful for identifying its causes and tendencies to develop, in turn providing scientific information for soil and water conservation at the regional scale. In the present study, the spatial and temporal patterns of soil erosion of a small agricultural watershed in central TGRR were investigated from 2002 to 2014 using the Revised Universal Soil Loss Equation (RUSLE) model, combined with Geographic Information Systems (GIS). The trends and processes of the overall soil erosion intensity were analyzed using spatial overlay analysis and the Markov transition matrix model, respectively. The spatial distribution of soil erosion rates within this watershed was relatively consistent during the study period. Erosion intensity was moderate, with a mean soil loss of 35.1 tha(-1)year(-1). Precipitation was a dominant factor influencing the intensity of soil erosion. Moreover, most erosion intensities shifted closely to middle grades from 2002 to 2008, and declined from 2008 to 2014, indicating that soil erosion in the Wangjiagou watershed has recently decreased. These results suggest that recently implemented integrated soil management practices were responsible for the recently observed erosion patterns.